1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice unmodified, this list of conditions, and the following 12 * disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * This file implements the ULE scheduler. ULE supports independent CPU 31 * run queues and fine grain locking. It has superior interactive 32 * performance under load even on uni-processor systems. 33 * 34 * etymology: 35 * ULE is the last three letters in schedule. It owes its name to a 36 * generic user created for a scheduling system by Paul Mikesell at 37 * Isilon Systems and a general lack of creativity on the part of the author. 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "opt_hwpmc_hooks.h" 44 #include "opt_sched.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/kdb.h> 49 #include <sys/kernel.h> 50 #include <sys/ktr.h> 51 #include <sys/limits.h> 52 #include <sys/lock.h> 53 #include <sys/mutex.h> 54 #include <sys/proc.h> 55 #include <sys/resource.h> 56 #include <sys/resourcevar.h> 57 #include <sys/sched.h> 58 #include <sys/sdt.h> 59 #include <sys/smp.h> 60 #include <sys/sx.h> 61 #include <sys/sysctl.h> 62 #include <sys/sysproto.h> 63 #include <sys/turnstile.h> 64 #include <sys/umtx.h> 65 #include <sys/vmmeter.h> 66 #include <sys/cpuset.h> 67 #include <sys/sbuf.h> 68 69 #ifdef HWPMC_HOOKS 70 #include <sys/pmckern.h> 71 #endif 72 73 #ifdef KDTRACE_HOOKS 74 #include <sys/dtrace_bsd.h> 75 int dtrace_vtime_active; 76 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 77 #endif 78 79 #include <machine/cpu.h> 80 #include <machine/smp.h> 81 82 #define KTR_ULE 0 83 84 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 85 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 86 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 87 88 /* 89 * Thread scheduler specific section. All fields are protected 90 * by the thread lock. 91 */ 92 struct td_sched { 93 struct runq *ts_runq; /* Run-queue we're queued on. */ 94 short ts_flags; /* TSF_* flags. */ 95 int ts_cpu; /* CPU that we have affinity for. */ 96 int ts_rltick; /* Real last tick, for affinity. */ 97 int ts_slice; /* Ticks of slice remaining. */ 98 u_int ts_slptime; /* Number of ticks we vol. slept */ 99 u_int ts_runtime; /* Number of ticks we were running */ 100 int ts_ltick; /* Last tick that we were running on */ 101 int ts_ftick; /* First tick that we were running on */ 102 int ts_ticks; /* Tick count */ 103 #ifdef KTR 104 char ts_name[TS_NAME_LEN]; 105 #endif 106 }; 107 /* flags kept in ts_flags */ 108 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 109 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 110 111 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 112 #define THREAD_CAN_SCHED(td, cpu) \ 113 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 114 115 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 116 sizeof(struct thread0_storage), 117 "increase struct thread0_storage.t0st_sched size"); 118 119 /* 120 * Priority ranges used for interactive and non-interactive timeshare 121 * threads. The timeshare priorities are split up into four ranges. 122 * The first range handles interactive threads. The last three ranges 123 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 124 * ranges supporting nice values. 125 */ 126 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 127 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 128 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 129 130 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 131 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 132 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 133 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 134 135 /* 136 * Cpu percentage computation macros and defines. 137 * 138 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 139 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 140 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 141 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 142 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 143 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 144 */ 145 #define SCHED_TICK_SECS 10 146 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 147 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 148 #define SCHED_TICK_SHIFT 10 149 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 150 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 151 152 /* 153 * These macros determine priorities for non-interactive threads. They are 154 * assigned a priority based on their recent cpu utilization as expressed 155 * by the ratio of ticks to the tick total. NHALF priorities at the start 156 * and end of the MIN to MAX timeshare range are only reachable with negative 157 * or positive nice respectively. 158 * 159 * PRI_RANGE: Priority range for utilization dependent priorities. 160 * PRI_NRESV: Number of nice values. 161 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 162 * PRI_NICE: Determines the part of the priority inherited from nice. 163 */ 164 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 165 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 166 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 167 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 168 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 169 #define SCHED_PRI_TICKS(ts) \ 170 (SCHED_TICK_HZ((ts)) / \ 171 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 172 #define SCHED_PRI_NICE(nice) (nice) 173 174 /* 175 * These determine the interactivity of a process. Interactivity differs from 176 * cpu utilization in that it expresses the voluntary time slept vs time ran 177 * while cpu utilization includes all time not running. This more accurately 178 * models the intent of the thread. 179 * 180 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 181 * before throttling back. 182 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 183 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 184 * INTERACT_THRESH: Threshold for placement on the current runq. 185 */ 186 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 187 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 188 #define SCHED_INTERACT_MAX (100) 189 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 190 #define SCHED_INTERACT_THRESH (30) 191 192 /* 193 * These parameters determine the slice behavior for batch work. 194 */ 195 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 196 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 197 198 /* Flags kept in td_flags. */ 199 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 200 201 /* 202 * tickincr: Converts a stathz tick into a hz domain scaled by 203 * the shift factor. Without the shift the error rate 204 * due to rounding would be unacceptably high. 205 * realstathz: stathz is sometimes 0 and run off of hz. 206 * sched_slice: Runtime of each thread before rescheduling. 207 * preempt_thresh: Priority threshold for preemption and remote IPIs. 208 */ 209 static int sched_interact = SCHED_INTERACT_THRESH; 210 static int tickincr = 8 << SCHED_TICK_SHIFT; 211 static int realstathz = 127; /* reset during boot. */ 212 static int sched_slice = 10; /* reset during boot. */ 213 static int sched_slice_min = 1; /* reset during boot. */ 214 #ifdef PREEMPTION 215 #ifdef FULL_PREEMPTION 216 static int preempt_thresh = PRI_MAX_IDLE; 217 #else 218 static int preempt_thresh = PRI_MIN_KERN; 219 #endif 220 #else 221 static int preempt_thresh = 0; 222 #endif 223 static int static_boost = PRI_MIN_BATCH; 224 static int sched_idlespins = 10000; 225 static int sched_idlespinthresh = -1; 226 227 /* 228 * tdq - per processor runqs and statistics. All fields are protected by the 229 * tdq_lock. The load and lowpri may be accessed without to avoid excess 230 * locking in sched_pickcpu(); 231 */ 232 struct tdq { 233 /* 234 * Ordered to improve efficiency of cpu_search() and switch(). 235 * tdq_lock is padded to avoid false sharing with tdq_load and 236 * tdq_cpu_idle. 237 */ 238 struct mtx_padalign tdq_lock; /* run queue lock. */ 239 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 240 volatile int tdq_load; /* Aggregate load. */ 241 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 242 int tdq_sysload; /* For loadavg, !ITHD load. */ 243 volatile int tdq_transferable; /* Transferable thread count. */ 244 volatile short tdq_switchcnt; /* Switches this tick. */ 245 volatile short tdq_oldswitchcnt; /* Switches last tick. */ 246 u_char tdq_lowpri; /* Lowest priority thread. */ 247 u_char tdq_ipipending; /* IPI pending. */ 248 u_char tdq_idx; /* Current insert index. */ 249 u_char tdq_ridx; /* Current removal index. */ 250 int tdq_id; /* cpuid. */ 251 struct runq tdq_realtime; /* real-time run queue. */ 252 struct runq tdq_timeshare; /* timeshare run queue. */ 253 struct runq tdq_idle; /* Queue of IDLE threads. */ 254 char tdq_name[TDQ_NAME_LEN]; 255 #ifdef KTR 256 char tdq_loadname[TDQ_LOADNAME_LEN]; 257 #endif 258 } __aligned(64); 259 260 /* Idle thread states and config. */ 261 #define TDQ_RUNNING 1 262 #define TDQ_IDLE 2 263 264 #ifdef SMP 265 struct cpu_group *cpu_top; /* CPU topology */ 266 267 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 268 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 269 270 /* 271 * Run-time tunables. 272 */ 273 static int rebalance = 1; 274 static int balance_interval = 128; /* Default set in sched_initticks(). */ 275 static int affinity; 276 static int steal_idle = 1; 277 static int steal_thresh = 2; 278 static int always_steal = 0; 279 static int trysteal_limit = 2; 280 281 /* 282 * One thread queue per processor. 283 */ 284 static struct tdq *balance_tdq; 285 static int balance_ticks; 286 DPCPU_DEFINE_STATIC(struct tdq, tdq); 287 DPCPU_DEFINE_STATIC(uint32_t, randomval); 288 289 #define TDQ_SELF() ((struct tdq *)PCPU_GET(sched)) 290 #define TDQ_CPU(x) (DPCPU_ID_PTR((x), tdq)) 291 #define TDQ_ID(x) ((x)->tdq_id) 292 #else /* !SMP */ 293 static struct tdq tdq_cpu; 294 295 #define TDQ_ID(x) (0) 296 #define TDQ_SELF() (&tdq_cpu) 297 #define TDQ_CPU(x) (&tdq_cpu) 298 #endif 299 300 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 301 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 302 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 303 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 304 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 305 306 static void sched_priority(struct thread *); 307 static void sched_thread_priority(struct thread *, u_char); 308 static int sched_interact_score(struct thread *); 309 static void sched_interact_update(struct thread *); 310 static void sched_interact_fork(struct thread *); 311 static void sched_pctcpu_update(struct td_sched *, int); 312 313 /* Operations on per processor queues */ 314 static struct thread *tdq_choose(struct tdq *); 315 static void tdq_setup(struct tdq *, int i); 316 static void tdq_load_add(struct tdq *, struct thread *); 317 static void tdq_load_rem(struct tdq *, struct thread *); 318 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 319 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 320 static inline int sched_shouldpreempt(int, int, int); 321 void tdq_print(int cpu); 322 static void runq_print(struct runq *rq); 323 static void tdq_add(struct tdq *, struct thread *, int); 324 #ifdef SMP 325 static struct thread *tdq_move(struct tdq *, struct tdq *); 326 static int tdq_idled(struct tdq *); 327 static void tdq_notify(struct tdq *, struct thread *); 328 static struct thread *tdq_steal(struct tdq *, int); 329 static struct thread *runq_steal(struct runq *, int); 330 static int sched_pickcpu(struct thread *, int); 331 static void sched_balance(void); 332 static int sched_balance_pair(struct tdq *, struct tdq *); 333 static inline struct tdq *sched_setcpu(struct thread *, int, int); 334 static inline void thread_unblock_switch(struct thread *, struct mtx *); 335 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 336 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 337 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 338 struct cpu_group *cg, int indent); 339 #endif 340 341 static void sched_setup(void *dummy); 342 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 343 344 static void sched_initticks(void *dummy); 345 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 346 NULL); 347 348 SDT_PROVIDER_DEFINE(sched); 349 350 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 351 "struct proc *", "uint8_t"); 352 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 353 "struct proc *", "void *"); 354 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 355 "struct proc *", "void *", "int"); 356 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 357 "struct proc *", "uint8_t", "struct thread *"); 358 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 359 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 360 "struct proc *"); 361 SDT_PROBE_DEFINE(sched, , , on__cpu); 362 SDT_PROBE_DEFINE(sched, , , remain__cpu); 363 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 364 "struct proc *"); 365 366 /* 367 * Print the threads waiting on a run-queue. 368 */ 369 static void 370 runq_print(struct runq *rq) 371 { 372 struct rqhead *rqh; 373 struct thread *td; 374 int pri; 375 int j; 376 int i; 377 378 for (i = 0; i < RQB_LEN; i++) { 379 printf("\t\trunq bits %d 0x%zx\n", 380 i, rq->rq_status.rqb_bits[i]); 381 for (j = 0; j < RQB_BPW; j++) 382 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 383 pri = j + (i << RQB_L2BPW); 384 rqh = &rq->rq_queues[pri]; 385 TAILQ_FOREACH(td, rqh, td_runq) { 386 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 387 td, td->td_name, td->td_priority, 388 td->td_rqindex, pri); 389 } 390 } 391 } 392 } 393 394 /* 395 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 396 */ 397 void 398 tdq_print(int cpu) 399 { 400 struct tdq *tdq; 401 402 tdq = TDQ_CPU(cpu); 403 404 printf("tdq %d:\n", TDQ_ID(tdq)); 405 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 406 printf("\tLock name: %s\n", tdq->tdq_name); 407 printf("\tload: %d\n", tdq->tdq_load); 408 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 409 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 410 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 411 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 412 printf("\tload transferable: %d\n", tdq->tdq_transferable); 413 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 414 printf("\trealtime runq:\n"); 415 runq_print(&tdq->tdq_realtime); 416 printf("\ttimeshare runq:\n"); 417 runq_print(&tdq->tdq_timeshare); 418 printf("\tidle runq:\n"); 419 runq_print(&tdq->tdq_idle); 420 } 421 422 static inline int 423 sched_shouldpreempt(int pri, int cpri, int remote) 424 { 425 /* 426 * If the new priority is not better than the current priority there is 427 * nothing to do. 428 */ 429 if (pri >= cpri) 430 return (0); 431 /* 432 * Always preempt idle. 433 */ 434 if (cpri >= PRI_MIN_IDLE) 435 return (1); 436 /* 437 * If preemption is disabled don't preempt others. 438 */ 439 if (preempt_thresh == 0) 440 return (0); 441 /* 442 * Preempt if we exceed the threshold. 443 */ 444 if (pri <= preempt_thresh) 445 return (1); 446 /* 447 * If we're interactive or better and there is non-interactive 448 * or worse running preempt only remote processors. 449 */ 450 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 451 return (1); 452 return (0); 453 } 454 455 /* 456 * Add a thread to the actual run-queue. Keeps transferable counts up to 457 * date with what is actually on the run-queue. Selects the correct 458 * queue position for timeshare threads. 459 */ 460 static __inline void 461 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 462 { 463 struct td_sched *ts; 464 u_char pri; 465 466 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 467 THREAD_LOCK_ASSERT(td, MA_OWNED); 468 469 pri = td->td_priority; 470 ts = td_get_sched(td); 471 TD_SET_RUNQ(td); 472 if (THREAD_CAN_MIGRATE(td)) { 473 tdq->tdq_transferable++; 474 ts->ts_flags |= TSF_XFERABLE; 475 } 476 if (pri < PRI_MIN_BATCH) { 477 ts->ts_runq = &tdq->tdq_realtime; 478 } else if (pri <= PRI_MAX_BATCH) { 479 ts->ts_runq = &tdq->tdq_timeshare; 480 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 481 ("Invalid priority %d on timeshare runq", pri)); 482 /* 483 * This queue contains only priorities between MIN and MAX 484 * realtime. Use the whole queue to represent these values. 485 */ 486 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 487 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 488 pri = (pri + tdq->tdq_idx) % RQ_NQS; 489 /* 490 * This effectively shortens the queue by one so we 491 * can have a one slot difference between idx and 492 * ridx while we wait for threads to drain. 493 */ 494 if (tdq->tdq_ridx != tdq->tdq_idx && 495 pri == tdq->tdq_ridx) 496 pri = (unsigned char)(pri - 1) % RQ_NQS; 497 } else 498 pri = tdq->tdq_ridx; 499 runq_add_pri(ts->ts_runq, td, pri, flags); 500 return; 501 } else 502 ts->ts_runq = &tdq->tdq_idle; 503 runq_add(ts->ts_runq, td, flags); 504 } 505 506 /* 507 * Remove a thread from a run-queue. This typically happens when a thread 508 * is selected to run. Running threads are not on the queue and the 509 * transferable count does not reflect them. 510 */ 511 static __inline void 512 tdq_runq_rem(struct tdq *tdq, struct thread *td) 513 { 514 struct td_sched *ts; 515 516 ts = td_get_sched(td); 517 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 518 KASSERT(ts->ts_runq != NULL, 519 ("tdq_runq_remove: thread %p null ts_runq", td)); 520 if (ts->ts_flags & TSF_XFERABLE) { 521 tdq->tdq_transferable--; 522 ts->ts_flags &= ~TSF_XFERABLE; 523 } 524 if (ts->ts_runq == &tdq->tdq_timeshare) { 525 if (tdq->tdq_idx != tdq->tdq_ridx) 526 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 527 else 528 runq_remove_idx(ts->ts_runq, td, NULL); 529 } else 530 runq_remove(ts->ts_runq, td); 531 } 532 533 /* 534 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 535 * for this thread to the referenced thread queue. 536 */ 537 static void 538 tdq_load_add(struct tdq *tdq, struct thread *td) 539 { 540 541 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 542 THREAD_LOCK_ASSERT(td, MA_OWNED); 543 544 tdq->tdq_load++; 545 if ((td->td_flags & TDF_NOLOAD) == 0) 546 tdq->tdq_sysload++; 547 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 548 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 549 } 550 551 /* 552 * Remove the load from a thread that is transitioning to a sleep state or 553 * exiting. 554 */ 555 static void 556 tdq_load_rem(struct tdq *tdq, struct thread *td) 557 { 558 559 THREAD_LOCK_ASSERT(td, MA_OWNED); 560 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 561 KASSERT(tdq->tdq_load != 0, 562 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 563 564 tdq->tdq_load--; 565 if ((td->td_flags & TDF_NOLOAD) == 0) 566 tdq->tdq_sysload--; 567 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 568 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 569 } 570 571 /* 572 * Bound timeshare latency by decreasing slice size as load increases. We 573 * consider the maximum latency as the sum of the threads waiting to run 574 * aside from curthread and target no more than sched_slice latency but 575 * no less than sched_slice_min runtime. 576 */ 577 static inline int 578 tdq_slice(struct tdq *tdq) 579 { 580 int load; 581 582 /* 583 * It is safe to use sys_load here because this is called from 584 * contexts where timeshare threads are running and so there 585 * cannot be higher priority load in the system. 586 */ 587 load = tdq->tdq_sysload - 1; 588 if (load >= SCHED_SLICE_MIN_DIVISOR) 589 return (sched_slice_min); 590 if (load <= 1) 591 return (sched_slice); 592 return (sched_slice / load); 593 } 594 595 /* 596 * Set lowpri to its exact value by searching the run-queue and 597 * evaluating curthread. curthread may be passed as an optimization. 598 */ 599 static void 600 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 601 { 602 struct thread *td; 603 604 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 605 if (ctd == NULL) 606 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 607 td = tdq_choose(tdq); 608 if (td == NULL || td->td_priority > ctd->td_priority) 609 tdq->tdq_lowpri = ctd->td_priority; 610 else 611 tdq->tdq_lowpri = td->td_priority; 612 } 613 614 #ifdef SMP 615 /* 616 * We need some randomness. Implement a classic Linear Congruential 617 * Generator X_{n+1}=(aX_n+c) mod m. These values are optimized for 618 * m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits 619 * of the random state (in the low bits of our answer) to keep 620 * the maximum randomness. 621 */ 622 static uint32_t 623 sched_random(void) 624 { 625 uint32_t *rndptr; 626 627 rndptr = DPCPU_PTR(randomval); 628 *rndptr = *rndptr * 69069 + 5; 629 630 return (*rndptr >> 16); 631 } 632 633 struct cpu_search { 634 cpuset_t cs_mask; 635 u_int cs_prefer; 636 int cs_pri; /* Min priority for low. */ 637 int cs_limit; /* Max load for low, min load for high. */ 638 int cs_cpu; 639 int cs_load; 640 }; 641 642 #define CPU_SEARCH_LOWEST 0x1 643 #define CPU_SEARCH_HIGHEST 0x2 644 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 645 646 #define CPUSET_FOREACH(cpu, mask) \ 647 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 648 if (CPU_ISSET(cpu, &mask)) 649 650 static __always_inline int cpu_search(const struct cpu_group *cg, 651 struct cpu_search *low, struct cpu_search *high, const int match); 652 int __noinline cpu_search_lowest(const struct cpu_group *cg, 653 struct cpu_search *low); 654 int __noinline cpu_search_highest(const struct cpu_group *cg, 655 struct cpu_search *high); 656 int __noinline cpu_search_both(const struct cpu_group *cg, 657 struct cpu_search *low, struct cpu_search *high); 658 659 /* 660 * Search the tree of cpu_groups for the lowest or highest loaded cpu 661 * according to the match argument. This routine actually compares the 662 * load on all paths through the tree and finds the least loaded cpu on 663 * the least loaded path, which may differ from the least loaded cpu in 664 * the system. This balances work among caches and buses. 665 * 666 * This inline is instantiated in three forms below using constants for the 667 * match argument. It is reduced to the minimum set for each case. It is 668 * also recursive to the depth of the tree. 669 */ 670 static __always_inline int 671 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 672 struct cpu_search *high, const int match) 673 { 674 struct cpu_search lgroup; 675 struct cpu_search hgroup; 676 cpuset_t cpumask; 677 struct cpu_group *child; 678 struct tdq *tdq; 679 int cpu, i, hload, lload, load, total, rnd; 680 681 total = 0; 682 cpumask = cg->cg_mask; 683 if (match & CPU_SEARCH_LOWEST) { 684 lload = INT_MAX; 685 lgroup = *low; 686 } 687 if (match & CPU_SEARCH_HIGHEST) { 688 hload = INT_MIN; 689 hgroup = *high; 690 } 691 692 /* Iterate through the child CPU groups and then remaining CPUs. */ 693 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 694 if (i == 0) { 695 #ifdef HAVE_INLINE_FFSL 696 cpu = CPU_FFS(&cpumask) - 1; 697 #else 698 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 699 cpu--; 700 #endif 701 if (cpu < 0) 702 break; 703 child = NULL; 704 } else 705 child = &cg->cg_child[i - 1]; 706 707 if (match & CPU_SEARCH_LOWEST) 708 lgroup.cs_cpu = -1; 709 if (match & CPU_SEARCH_HIGHEST) 710 hgroup.cs_cpu = -1; 711 if (child) { /* Handle child CPU group. */ 712 CPU_NAND(&cpumask, &child->cg_mask); 713 switch (match) { 714 case CPU_SEARCH_LOWEST: 715 load = cpu_search_lowest(child, &lgroup); 716 break; 717 case CPU_SEARCH_HIGHEST: 718 load = cpu_search_highest(child, &hgroup); 719 break; 720 case CPU_SEARCH_BOTH: 721 load = cpu_search_both(child, &lgroup, &hgroup); 722 break; 723 } 724 } else { /* Handle child CPU. */ 725 CPU_CLR(cpu, &cpumask); 726 tdq = TDQ_CPU(cpu); 727 load = tdq->tdq_load * 256; 728 rnd = sched_random() % 32; 729 if (match & CPU_SEARCH_LOWEST) { 730 if (cpu == low->cs_prefer) 731 load -= 64; 732 /* If that CPU is allowed and get data. */ 733 if (tdq->tdq_lowpri > lgroup.cs_pri && 734 tdq->tdq_load <= lgroup.cs_limit && 735 CPU_ISSET(cpu, &lgroup.cs_mask)) { 736 lgroup.cs_cpu = cpu; 737 lgroup.cs_load = load - rnd; 738 } 739 } 740 if (match & CPU_SEARCH_HIGHEST) 741 if (tdq->tdq_load >= hgroup.cs_limit && 742 tdq->tdq_transferable && 743 CPU_ISSET(cpu, &hgroup.cs_mask)) { 744 hgroup.cs_cpu = cpu; 745 hgroup.cs_load = load - rnd; 746 } 747 } 748 total += load; 749 750 /* We have info about child item. Compare it. */ 751 if (match & CPU_SEARCH_LOWEST) { 752 if (lgroup.cs_cpu >= 0 && 753 (load < lload || 754 (load == lload && lgroup.cs_load < low->cs_load))) { 755 lload = load; 756 low->cs_cpu = lgroup.cs_cpu; 757 low->cs_load = lgroup.cs_load; 758 } 759 } 760 if (match & CPU_SEARCH_HIGHEST) 761 if (hgroup.cs_cpu >= 0 && 762 (load > hload || 763 (load == hload && hgroup.cs_load > high->cs_load))) { 764 hload = load; 765 high->cs_cpu = hgroup.cs_cpu; 766 high->cs_load = hgroup.cs_load; 767 } 768 if (child) { 769 i--; 770 if (i == 0 && CPU_EMPTY(&cpumask)) 771 break; 772 } 773 #ifndef HAVE_INLINE_FFSL 774 else 775 cpu--; 776 #endif 777 } 778 return (total); 779 } 780 781 /* 782 * cpu_search instantiations must pass constants to maintain the inline 783 * optimization. 784 */ 785 int 786 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 787 { 788 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 789 } 790 791 int 792 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 793 { 794 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 795 } 796 797 int 798 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 799 struct cpu_search *high) 800 { 801 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 802 } 803 804 /* 805 * Find the cpu with the least load via the least loaded path that has a 806 * lowpri greater than pri pri. A pri of -1 indicates any priority is 807 * acceptable. 808 */ 809 static inline int 810 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 811 int prefer) 812 { 813 struct cpu_search low; 814 815 low.cs_cpu = -1; 816 low.cs_prefer = prefer; 817 low.cs_mask = mask; 818 low.cs_pri = pri; 819 low.cs_limit = maxload; 820 cpu_search_lowest(cg, &low); 821 return low.cs_cpu; 822 } 823 824 /* 825 * Find the cpu with the highest load via the highest loaded path. 826 */ 827 static inline int 828 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 829 { 830 struct cpu_search high; 831 832 high.cs_cpu = -1; 833 high.cs_mask = mask; 834 high.cs_limit = minload; 835 cpu_search_highest(cg, &high); 836 return high.cs_cpu; 837 } 838 839 static void 840 sched_balance_group(struct cpu_group *cg) 841 { 842 struct tdq *tdq; 843 cpuset_t hmask, lmask; 844 int high, low, anylow; 845 846 CPU_FILL(&hmask); 847 for (;;) { 848 high = sched_highest(cg, hmask, 2); 849 /* Stop if there is no more CPU with transferrable threads. */ 850 if (high == -1) 851 break; 852 CPU_CLR(high, &hmask); 853 CPU_COPY(&hmask, &lmask); 854 /* Stop if there is no more CPU left for low. */ 855 if (CPU_EMPTY(&lmask)) 856 break; 857 anylow = 1; 858 tdq = TDQ_CPU(high); 859 nextlow: 860 low = sched_lowest(cg, lmask, -1, tdq->tdq_load - 1, high); 861 /* Stop if we looked well and found no less loaded CPU. */ 862 if (anylow && low == -1) 863 break; 864 /* Go to next high if we found no less loaded CPU. */ 865 if (low == -1) 866 continue; 867 /* Transfer thread from high to low. */ 868 if (sched_balance_pair(tdq, TDQ_CPU(low))) { 869 /* CPU that got thread can no longer be a donor. */ 870 CPU_CLR(low, &hmask); 871 } else { 872 /* 873 * If failed, then there is no threads on high 874 * that can run on this low. Drop low from low 875 * mask and look for different one. 876 */ 877 CPU_CLR(low, &lmask); 878 anylow = 0; 879 goto nextlow; 880 } 881 } 882 } 883 884 static void 885 sched_balance(void) 886 { 887 struct tdq *tdq; 888 889 balance_ticks = max(balance_interval / 2, 1) + 890 (sched_random() % balance_interval); 891 tdq = TDQ_SELF(); 892 TDQ_UNLOCK(tdq); 893 sched_balance_group(cpu_top); 894 TDQ_LOCK(tdq); 895 } 896 897 /* 898 * Lock two thread queues using their address to maintain lock order. 899 */ 900 static void 901 tdq_lock_pair(struct tdq *one, struct tdq *two) 902 { 903 if (one < two) { 904 TDQ_LOCK(one); 905 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 906 } else { 907 TDQ_LOCK(two); 908 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 909 } 910 } 911 912 /* 913 * Unlock two thread queues. Order is not important here. 914 */ 915 static void 916 tdq_unlock_pair(struct tdq *one, struct tdq *two) 917 { 918 TDQ_UNLOCK(one); 919 TDQ_UNLOCK(two); 920 } 921 922 /* 923 * Transfer load between two imbalanced thread queues. 924 */ 925 static int 926 sched_balance_pair(struct tdq *high, struct tdq *low) 927 { 928 struct thread *td; 929 int cpu; 930 931 tdq_lock_pair(high, low); 932 td = NULL; 933 /* 934 * Transfer a thread from high to low. 935 */ 936 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 937 (td = tdq_move(high, low)) != NULL) { 938 /* 939 * In case the target isn't the current cpu notify it of the 940 * new load, possibly sending an IPI to force it to reschedule. 941 */ 942 cpu = TDQ_ID(low); 943 if (cpu != PCPU_GET(cpuid)) 944 tdq_notify(low, td); 945 } 946 tdq_unlock_pair(high, low); 947 return (td != NULL); 948 } 949 950 /* 951 * Move a thread from one thread queue to another. 952 */ 953 static struct thread * 954 tdq_move(struct tdq *from, struct tdq *to) 955 { 956 struct td_sched *ts; 957 struct thread *td; 958 struct tdq *tdq; 959 int cpu; 960 961 TDQ_LOCK_ASSERT(from, MA_OWNED); 962 TDQ_LOCK_ASSERT(to, MA_OWNED); 963 964 tdq = from; 965 cpu = TDQ_ID(to); 966 td = tdq_steal(tdq, cpu); 967 if (td == NULL) 968 return (NULL); 969 ts = td_get_sched(td); 970 /* 971 * Although the run queue is locked the thread may be blocked. Lock 972 * it to clear this and acquire the run-queue lock. 973 */ 974 thread_lock(td); 975 /* Drop recursive lock on from acquired via thread_lock(). */ 976 TDQ_UNLOCK(from); 977 sched_rem(td); 978 ts->ts_cpu = cpu; 979 td->td_lock = TDQ_LOCKPTR(to); 980 tdq_add(to, td, SRQ_YIELDING); 981 return (td); 982 } 983 984 /* 985 * This tdq has idled. Try to steal a thread from another cpu and switch 986 * to it. 987 */ 988 static int 989 tdq_idled(struct tdq *tdq) 990 { 991 struct cpu_group *cg; 992 struct tdq *steal; 993 cpuset_t mask; 994 int cpu, switchcnt; 995 996 if (smp_started == 0 || steal_idle == 0 || tdq->tdq_cg == NULL) 997 return (1); 998 CPU_FILL(&mask); 999 CPU_CLR(PCPU_GET(cpuid), &mask); 1000 restart: 1001 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 1002 for (cg = tdq->tdq_cg; ; ) { 1003 cpu = sched_highest(cg, mask, steal_thresh); 1004 /* 1005 * We were assigned a thread but not preempted. Returning 1006 * 0 here will cause our caller to switch to it. 1007 */ 1008 if (tdq->tdq_load) 1009 return (0); 1010 if (cpu == -1) { 1011 cg = cg->cg_parent; 1012 if (cg == NULL) 1013 return (1); 1014 continue; 1015 } 1016 steal = TDQ_CPU(cpu); 1017 /* 1018 * The data returned by sched_highest() is stale and 1019 * the chosen CPU no longer has an eligible thread. 1020 * 1021 * Testing this ahead of tdq_lock_pair() only catches 1022 * this situation about 20% of the time on an 8 core 1023 * 16 thread Ryzen 7, but it still helps performance. 1024 */ 1025 if (steal->tdq_load < steal_thresh || 1026 steal->tdq_transferable == 0) 1027 goto restart; 1028 tdq_lock_pair(tdq, steal); 1029 /* 1030 * We were assigned a thread while waiting for the locks. 1031 * Switch to it now instead of stealing a thread. 1032 */ 1033 if (tdq->tdq_load) 1034 break; 1035 /* 1036 * The data returned by sched_highest() is stale and 1037 * the chosen CPU no longer has an eligible thread, or 1038 * we were preempted and the CPU loading info may be out 1039 * of date. The latter is rare. In either case restart 1040 * the search. 1041 */ 1042 if (steal->tdq_load < steal_thresh || 1043 steal->tdq_transferable == 0 || 1044 switchcnt != tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt) { 1045 tdq_unlock_pair(tdq, steal); 1046 goto restart; 1047 } 1048 /* 1049 * Steal the thread and switch to it. 1050 */ 1051 if (tdq_move(steal, tdq) != NULL) 1052 break; 1053 /* 1054 * We failed to acquire a thread even though it looked 1055 * like one was available. This could be due to affinity 1056 * restrictions or for other reasons. Loop again after 1057 * removing this CPU from the set. The restart logic 1058 * above does not restore this CPU to the set due to the 1059 * likelyhood of failing here again. 1060 */ 1061 CPU_CLR(cpu, &mask); 1062 tdq_unlock_pair(tdq, steal); 1063 } 1064 TDQ_UNLOCK(steal); 1065 mi_switch(SW_VOL | SWT_IDLE, NULL); 1066 thread_unlock(curthread); 1067 return (0); 1068 } 1069 1070 /* 1071 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1072 */ 1073 static void 1074 tdq_notify(struct tdq *tdq, struct thread *td) 1075 { 1076 struct thread *ctd; 1077 int pri; 1078 int cpu; 1079 1080 if (tdq->tdq_ipipending) 1081 return; 1082 cpu = td_get_sched(td)->ts_cpu; 1083 pri = td->td_priority; 1084 ctd = pcpu_find(cpu)->pc_curthread; 1085 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1086 return; 1087 1088 /* 1089 * Make sure that our caller's earlier update to tdq_load is 1090 * globally visible before we read tdq_cpu_idle. Idle thread 1091 * accesses both of them without locks, and the order is important. 1092 */ 1093 atomic_thread_fence_seq_cst(); 1094 1095 if (TD_IS_IDLETHREAD(ctd)) { 1096 /* 1097 * If the MD code has an idle wakeup routine try that before 1098 * falling back to IPI. 1099 */ 1100 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1101 return; 1102 } 1103 tdq->tdq_ipipending = 1; 1104 ipi_cpu(cpu, IPI_PREEMPT); 1105 } 1106 1107 /* 1108 * Steals load from a timeshare queue. Honors the rotating queue head 1109 * index. 1110 */ 1111 static struct thread * 1112 runq_steal_from(struct runq *rq, int cpu, u_char start) 1113 { 1114 struct rqbits *rqb; 1115 struct rqhead *rqh; 1116 struct thread *td, *first; 1117 int bit; 1118 int i; 1119 1120 rqb = &rq->rq_status; 1121 bit = start & (RQB_BPW -1); 1122 first = NULL; 1123 again: 1124 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1125 if (rqb->rqb_bits[i] == 0) 1126 continue; 1127 if (bit == 0) 1128 bit = RQB_FFS(rqb->rqb_bits[i]); 1129 for (; bit < RQB_BPW; bit++) { 1130 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1131 continue; 1132 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1133 TAILQ_FOREACH(td, rqh, td_runq) { 1134 if (first && THREAD_CAN_MIGRATE(td) && 1135 THREAD_CAN_SCHED(td, cpu)) 1136 return (td); 1137 first = td; 1138 } 1139 } 1140 } 1141 if (start != 0) { 1142 start = 0; 1143 goto again; 1144 } 1145 1146 if (first && THREAD_CAN_MIGRATE(first) && 1147 THREAD_CAN_SCHED(first, cpu)) 1148 return (first); 1149 return (NULL); 1150 } 1151 1152 /* 1153 * Steals load from a standard linear queue. 1154 */ 1155 static struct thread * 1156 runq_steal(struct runq *rq, int cpu) 1157 { 1158 struct rqhead *rqh; 1159 struct rqbits *rqb; 1160 struct thread *td; 1161 int word; 1162 int bit; 1163 1164 rqb = &rq->rq_status; 1165 for (word = 0; word < RQB_LEN; word++) { 1166 if (rqb->rqb_bits[word] == 0) 1167 continue; 1168 for (bit = 0; bit < RQB_BPW; bit++) { 1169 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1170 continue; 1171 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1172 TAILQ_FOREACH(td, rqh, td_runq) 1173 if (THREAD_CAN_MIGRATE(td) && 1174 THREAD_CAN_SCHED(td, cpu)) 1175 return (td); 1176 } 1177 } 1178 return (NULL); 1179 } 1180 1181 /* 1182 * Attempt to steal a thread in priority order from a thread queue. 1183 */ 1184 static struct thread * 1185 tdq_steal(struct tdq *tdq, int cpu) 1186 { 1187 struct thread *td; 1188 1189 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1190 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1191 return (td); 1192 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1193 cpu, tdq->tdq_ridx)) != NULL) 1194 return (td); 1195 return (runq_steal(&tdq->tdq_idle, cpu)); 1196 } 1197 1198 /* 1199 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1200 * current lock and returns with the assigned queue locked. 1201 */ 1202 static inline struct tdq * 1203 sched_setcpu(struct thread *td, int cpu, int flags) 1204 { 1205 1206 struct tdq *tdq; 1207 1208 THREAD_LOCK_ASSERT(td, MA_OWNED); 1209 tdq = TDQ_CPU(cpu); 1210 td_get_sched(td)->ts_cpu = cpu; 1211 /* 1212 * If the lock matches just return the queue. 1213 */ 1214 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1215 return (tdq); 1216 #ifdef notyet 1217 /* 1218 * If the thread isn't running its lockptr is a 1219 * turnstile or a sleepqueue. We can just lock_set without 1220 * blocking. 1221 */ 1222 if (TD_CAN_RUN(td)) { 1223 TDQ_LOCK(tdq); 1224 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1225 return (tdq); 1226 } 1227 #endif 1228 /* 1229 * The hard case, migration, we need to block the thread first to 1230 * prevent order reversals with other cpus locks. 1231 */ 1232 spinlock_enter(); 1233 thread_lock_block(td); 1234 TDQ_LOCK(tdq); 1235 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1236 spinlock_exit(); 1237 return (tdq); 1238 } 1239 1240 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1241 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1242 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1243 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1244 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1245 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1246 1247 static int 1248 sched_pickcpu(struct thread *td, int flags) 1249 { 1250 struct cpu_group *cg, *ccg; 1251 struct td_sched *ts; 1252 struct tdq *tdq; 1253 cpuset_t mask; 1254 int cpu, pri, self, intr; 1255 1256 self = PCPU_GET(cpuid); 1257 ts = td_get_sched(td); 1258 KASSERT(!CPU_ABSENT(ts->ts_cpu), ("sched_pickcpu: Start scheduler on " 1259 "absent CPU %d for thread %s.", ts->ts_cpu, td->td_name)); 1260 if (smp_started == 0) 1261 return (self); 1262 /* 1263 * Don't migrate a running thread from sched_switch(). 1264 */ 1265 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1266 return (ts->ts_cpu); 1267 /* 1268 * Prefer to run interrupt threads on the processors that generate 1269 * the interrupt. 1270 */ 1271 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1272 curthread->td_intr_nesting_level) { 1273 ts->ts_cpu = self; 1274 intr = 1; 1275 } else 1276 intr = 0; 1277 /* 1278 * If the thread can run on the last cpu and the affinity has not 1279 * expired and it is idle, run it there. 1280 */ 1281 tdq = TDQ_CPU(ts->ts_cpu); 1282 cg = tdq->tdq_cg; 1283 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1284 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1285 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1286 if (!intr && cg->cg_flags & CG_FLAG_THREAD) { 1287 CPUSET_FOREACH(cpu, cg->cg_mask) { 1288 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1289 break; 1290 } 1291 } else 1292 cpu = INT_MAX; 1293 if (cpu > mp_maxid) { 1294 SCHED_STAT_INC(pickcpu_idle_affinity); 1295 return (ts->ts_cpu); 1296 } 1297 } 1298 /* 1299 * Search for the last level cache CPU group in the tree. 1300 * Skip SMT, identical groups and caches with expired affinity. 1301 * Interrupt threads affinity is explicit and never expires. 1302 */ 1303 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1304 if (cg->cg_flags & CG_FLAG_THREAD) 1305 continue; 1306 if (cg->cg_children == 1 || cg->cg_count == 1) 1307 continue; 1308 if (cg->cg_level == CG_SHARE_NONE || 1309 (!intr && !SCHED_AFFINITY(ts, cg->cg_level))) 1310 continue; 1311 ccg = cg; 1312 } 1313 /* Found LLC shared by all CPUs, so do a global search. */ 1314 if (ccg == cpu_top) 1315 ccg = NULL; 1316 cpu = -1; 1317 mask = td->td_cpuset->cs_mask; 1318 pri = td->td_priority; 1319 /* 1320 * Try hard to keep interrupts within found LLC. Search the LLC for 1321 * the least loaded CPU we can run now. For NUMA systems it should 1322 * be within target domain, and it also reduces scheduling overhead. 1323 */ 1324 if (ccg != NULL && intr) { 1325 cpu = sched_lowest(ccg, mask, pri, INT_MAX, ts->ts_cpu); 1326 if (cpu >= 0) 1327 SCHED_STAT_INC(pickcpu_intrbind); 1328 } else 1329 /* Search the LLC for the least loaded idle CPU we can run now. */ 1330 if (ccg != NULL) { 1331 cpu = sched_lowest(ccg, mask, max(pri, PRI_MAX_TIMESHARE), 1332 INT_MAX, ts->ts_cpu); 1333 if (cpu >= 0) 1334 SCHED_STAT_INC(pickcpu_affinity); 1335 } 1336 /* Search globally for the least loaded CPU we can run now. */ 1337 if (cpu < 0) { 1338 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1339 if (cpu >= 0) 1340 SCHED_STAT_INC(pickcpu_lowest); 1341 } 1342 /* Search globally for the least loaded CPU. */ 1343 if (cpu < 0) { 1344 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1345 if (cpu >= 0) 1346 SCHED_STAT_INC(pickcpu_lowest); 1347 } 1348 KASSERT(cpu >= 0, ("sched_pickcpu: Failed to find a cpu.")); 1349 KASSERT(!CPU_ABSENT(cpu), ("sched_pickcpu: Picked absent CPU %d.", cpu)); 1350 /* 1351 * Compare the lowest loaded cpu to current cpu. 1352 */ 1353 tdq = TDQ_CPU(cpu); 1354 if (THREAD_CAN_SCHED(td, self) && TDQ_SELF()->tdq_lowpri > pri && 1355 tdq->tdq_lowpri < PRI_MIN_IDLE && 1356 TDQ_SELF()->tdq_load <= tdq->tdq_load + 1) { 1357 SCHED_STAT_INC(pickcpu_local); 1358 cpu = self; 1359 } 1360 if (cpu != ts->ts_cpu) 1361 SCHED_STAT_INC(pickcpu_migration); 1362 return (cpu); 1363 } 1364 #endif 1365 1366 /* 1367 * Pick the highest priority task we have and return it. 1368 */ 1369 static struct thread * 1370 tdq_choose(struct tdq *tdq) 1371 { 1372 struct thread *td; 1373 1374 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1375 td = runq_choose(&tdq->tdq_realtime); 1376 if (td != NULL) 1377 return (td); 1378 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1379 if (td != NULL) { 1380 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1381 ("tdq_choose: Invalid priority on timeshare queue %d", 1382 td->td_priority)); 1383 return (td); 1384 } 1385 td = runq_choose(&tdq->tdq_idle); 1386 if (td != NULL) { 1387 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1388 ("tdq_choose: Invalid priority on idle queue %d", 1389 td->td_priority)); 1390 return (td); 1391 } 1392 1393 return (NULL); 1394 } 1395 1396 /* 1397 * Initialize a thread queue. 1398 */ 1399 static void 1400 tdq_setup(struct tdq *tdq, int id) 1401 { 1402 1403 if (bootverbose) 1404 printf("ULE: setup cpu %d\n", id); 1405 runq_init(&tdq->tdq_realtime); 1406 runq_init(&tdq->tdq_timeshare); 1407 runq_init(&tdq->tdq_idle); 1408 tdq->tdq_id = id; 1409 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1410 "sched lock %d", (int)TDQ_ID(tdq)); 1411 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1412 MTX_SPIN | MTX_RECURSE); 1413 #ifdef KTR 1414 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1415 "CPU %d load", (int)TDQ_ID(tdq)); 1416 #endif 1417 } 1418 1419 #ifdef SMP 1420 static void 1421 sched_setup_smp(void) 1422 { 1423 struct tdq *tdq; 1424 int i; 1425 1426 cpu_top = smp_topo(); 1427 CPU_FOREACH(i) { 1428 tdq = DPCPU_ID_PTR(i, tdq); 1429 tdq_setup(tdq, i); 1430 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1431 if (tdq->tdq_cg == NULL) 1432 panic("Can't find cpu group for %d\n", i); 1433 } 1434 PCPU_SET(sched, DPCPU_PTR(tdq)); 1435 balance_tdq = TDQ_SELF(); 1436 } 1437 #endif 1438 1439 /* 1440 * Setup the thread queues and initialize the topology based on MD 1441 * information. 1442 */ 1443 static void 1444 sched_setup(void *dummy) 1445 { 1446 struct tdq *tdq; 1447 1448 #ifdef SMP 1449 sched_setup_smp(); 1450 #else 1451 tdq_setup(TDQ_SELF(), 0); 1452 #endif 1453 tdq = TDQ_SELF(); 1454 1455 /* Add thread0's load since it's running. */ 1456 TDQ_LOCK(tdq); 1457 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1458 tdq_load_add(tdq, &thread0); 1459 tdq->tdq_lowpri = thread0.td_priority; 1460 TDQ_UNLOCK(tdq); 1461 } 1462 1463 /* 1464 * This routine determines time constants after stathz and hz are setup. 1465 */ 1466 /* ARGSUSED */ 1467 static void 1468 sched_initticks(void *dummy) 1469 { 1470 int incr; 1471 1472 realstathz = stathz ? stathz : hz; 1473 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1474 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1475 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1476 realstathz); 1477 1478 /* 1479 * tickincr is shifted out by 10 to avoid rounding errors due to 1480 * hz not being evenly divisible by stathz on all platforms. 1481 */ 1482 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1483 /* 1484 * This does not work for values of stathz that are more than 1485 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1486 */ 1487 if (incr == 0) 1488 incr = 1; 1489 tickincr = incr; 1490 #ifdef SMP 1491 /* 1492 * Set the default balance interval now that we know 1493 * what realstathz is. 1494 */ 1495 balance_interval = realstathz; 1496 balance_ticks = balance_interval; 1497 affinity = SCHED_AFFINITY_DEFAULT; 1498 #endif 1499 if (sched_idlespinthresh < 0) 1500 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1501 } 1502 1503 1504 /* 1505 * This is the core of the interactivity algorithm. Determines a score based 1506 * on past behavior. It is the ratio of sleep time to run time scaled to 1507 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1508 * differs from the cpu usage because it does not account for time spent 1509 * waiting on a run-queue. Would be prettier if we had floating point. 1510 * 1511 * When a thread's sleep time is greater than its run time the 1512 * calculation is: 1513 * 1514 * scaling factor 1515 * interactivity score = --------------------- 1516 * sleep time / run time 1517 * 1518 * 1519 * When a thread's run time is greater than its sleep time the 1520 * calculation is: 1521 * 1522 * scaling factor 1523 * interactivity score = --------------------- + scaling factor 1524 * run time / sleep time 1525 */ 1526 static int 1527 sched_interact_score(struct thread *td) 1528 { 1529 struct td_sched *ts; 1530 int div; 1531 1532 ts = td_get_sched(td); 1533 /* 1534 * The score is only needed if this is likely to be an interactive 1535 * task. Don't go through the expense of computing it if there's 1536 * no chance. 1537 */ 1538 if (sched_interact <= SCHED_INTERACT_HALF && 1539 ts->ts_runtime >= ts->ts_slptime) 1540 return (SCHED_INTERACT_HALF); 1541 1542 if (ts->ts_runtime > ts->ts_slptime) { 1543 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1544 return (SCHED_INTERACT_HALF + 1545 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1546 } 1547 if (ts->ts_slptime > ts->ts_runtime) { 1548 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1549 return (ts->ts_runtime / div); 1550 } 1551 /* runtime == slptime */ 1552 if (ts->ts_runtime) 1553 return (SCHED_INTERACT_HALF); 1554 1555 /* 1556 * This can happen if slptime and runtime are 0. 1557 */ 1558 return (0); 1559 1560 } 1561 1562 /* 1563 * Scale the scheduling priority according to the "interactivity" of this 1564 * process. 1565 */ 1566 static void 1567 sched_priority(struct thread *td) 1568 { 1569 int score; 1570 int pri; 1571 1572 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1573 return; 1574 /* 1575 * If the score is interactive we place the thread in the realtime 1576 * queue with a priority that is less than kernel and interrupt 1577 * priorities. These threads are not subject to nice restrictions. 1578 * 1579 * Scores greater than this are placed on the normal timeshare queue 1580 * where the priority is partially decided by the most recent cpu 1581 * utilization and the rest is decided by nice value. 1582 * 1583 * The nice value of the process has a linear effect on the calculated 1584 * score. Negative nice values make it easier for a thread to be 1585 * considered interactive. 1586 */ 1587 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1588 if (score < sched_interact) { 1589 pri = PRI_MIN_INTERACT; 1590 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1591 sched_interact) * score; 1592 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1593 ("sched_priority: invalid interactive priority %d score %d", 1594 pri, score)); 1595 } else { 1596 pri = SCHED_PRI_MIN; 1597 if (td_get_sched(td)->ts_ticks) 1598 pri += min(SCHED_PRI_TICKS(td_get_sched(td)), 1599 SCHED_PRI_RANGE - 1); 1600 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1601 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1602 ("sched_priority: invalid priority %d: nice %d, " 1603 "ticks %d ftick %d ltick %d tick pri %d", 1604 pri, td->td_proc->p_nice, td_get_sched(td)->ts_ticks, 1605 td_get_sched(td)->ts_ftick, td_get_sched(td)->ts_ltick, 1606 SCHED_PRI_TICKS(td_get_sched(td)))); 1607 } 1608 sched_user_prio(td, pri); 1609 1610 return; 1611 } 1612 1613 /* 1614 * This routine enforces a maximum limit on the amount of scheduling history 1615 * kept. It is called after either the slptime or runtime is adjusted. This 1616 * function is ugly due to integer math. 1617 */ 1618 static void 1619 sched_interact_update(struct thread *td) 1620 { 1621 struct td_sched *ts; 1622 u_int sum; 1623 1624 ts = td_get_sched(td); 1625 sum = ts->ts_runtime + ts->ts_slptime; 1626 if (sum < SCHED_SLP_RUN_MAX) 1627 return; 1628 /* 1629 * This only happens from two places: 1630 * 1) We have added an unusual amount of run time from fork_exit. 1631 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1632 */ 1633 if (sum > SCHED_SLP_RUN_MAX * 2) { 1634 if (ts->ts_runtime > ts->ts_slptime) { 1635 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1636 ts->ts_slptime = 1; 1637 } else { 1638 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1639 ts->ts_runtime = 1; 1640 } 1641 return; 1642 } 1643 /* 1644 * If we have exceeded by more than 1/5th then the algorithm below 1645 * will not bring us back into range. Dividing by two here forces 1646 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1647 */ 1648 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1649 ts->ts_runtime /= 2; 1650 ts->ts_slptime /= 2; 1651 return; 1652 } 1653 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1654 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1655 } 1656 1657 /* 1658 * Scale back the interactivity history when a child thread is created. The 1659 * history is inherited from the parent but the thread may behave totally 1660 * differently. For example, a shell spawning a compiler process. We want 1661 * to learn that the compiler is behaving badly very quickly. 1662 */ 1663 static void 1664 sched_interact_fork(struct thread *td) 1665 { 1666 struct td_sched *ts; 1667 int ratio; 1668 int sum; 1669 1670 ts = td_get_sched(td); 1671 sum = ts->ts_runtime + ts->ts_slptime; 1672 if (sum > SCHED_SLP_RUN_FORK) { 1673 ratio = sum / SCHED_SLP_RUN_FORK; 1674 ts->ts_runtime /= ratio; 1675 ts->ts_slptime /= ratio; 1676 } 1677 } 1678 1679 /* 1680 * Called from proc0_init() to setup the scheduler fields. 1681 */ 1682 void 1683 schedinit(void) 1684 { 1685 struct td_sched *ts0; 1686 1687 /* 1688 * Set up the scheduler specific parts of thread0. 1689 */ 1690 ts0 = td_get_sched(&thread0); 1691 ts0->ts_ltick = ticks; 1692 ts0->ts_ftick = ticks; 1693 ts0->ts_slice = 0; 1694 ts0->ts_cpu = curcpu; /* set valid CPU number */ 1695 } 1696 1697 /* 1698 * This is only somewhat accurate since given many processes of the same 1699 * priority they will switch when their slices run out, which will be 1700 * at most sched_slice stathz ticks. 1701 */ 1702 int 1703 sched_rr_interval(void) 1704 { 1705 1706 /* Convert sched_slice from stathz to hz. */ 1707 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1708 } 1709 1710 /* 1711 * Update the percent cpu tracking information when it is requested or 1712 * the total history exceeds the maximum. We keep a sliding history of 1713 * tick counts that slowly decays. This is less precise than the 4BSD 1714 * mechanism since it happens with less regular and frequent events. 1715 */ 1716 static void 1717 sched_pctcpu_update(struct td_sched *ts, int run) 1718 { 1719 int t = ticks; 1720 1721 /* 1722 * The signed difference may be negative if the thread hasn't run for 1723 * over half of the ticks rollover period. 1724 */ 1725 if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) { 1726 ts->ts_ticks = 0; 1727 ts->ts_ftick = t - SCHED_TICK_TARG; 1728 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1729 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1730 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1731 ts->ts_ftick = t - SCHED_TICK_TARG; 1732 } 1733 if (run) 1734 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1735 ts->ts_ltick = t; 1736 } 1737 1738 /* 1739 * Adjust the priority of a thread. Move it to the appropriate run-queue 1740 * if necessary. This is the back-end for several priority related 1741 * functions. 1742 */ 1743 static void 1744 sched_thread_priority(struct thread *td, u_char prio) 1745 { 1746 struct td_sched *ts; 1747 struct tdq *tdq; 1748 int oldpri; 1749 1750 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1751 "prio:%d", td->td_priority, "new prio:%d", prio, 1752 KTR_ATTR_LINKED, sched_tdname(curthread)); 1753 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1754 if (td != curthread && prio < td->td_priority) { 1755 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1756 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1757 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1758 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1759 curthread); 1760 } 1761 ts = td_get_sched(td); 1762 THREAD_LOCK_ASSERT(td, MA_OWNED); 1763 if (td->td_priority == prio) 1764 return; 1765 /* 1766 * If the priority has been elevated due to priority 1767 * propagation, we may have to move ourselves to a new 1768 * queue. This could be optimized to not re-add in some 1769 * cases. 1770 */ 1771 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1772 sched_rem(td); 1773 td->td_priority = prio; 1774 sched_add(td, SRQ_BORROWING); 1775 return; 1776 } 1777 /* 1778 * If the thread is currently running we may have to adjust the lowpri 1779 * information so other cpus are aware of our current priority. 1780 */ 1781 if (TD_IS_RUNNING(td)) { 1782 tdq = TDQ_CPU(ts->ts_cpu); 1783 oldpri = td->td_priority; 1784 td->td_priority = prio; 1785 if (prio < tdq->tdq_lowpri) 1786 tdq->tdq_lowpri = prio; 1787 else if (tdq->tdq_lowpri == oldpri) 1788 tdq_setlowpri(tdq, td); 1789 return; 1790 } 1791 td->td_priority = prio; 1792 } 1793 1794 /* 1795 * Update a thread's priority when it is lent another thread's 1796 * priority. 1797 */ 1798 void 1799 sched_lend_prio(struct thread *td, u_char prio) 1800 { 1801 1802 td->td_flags |= TDF_BORROWING; 1803 sched_thread_priority(td, prio); 1804 } 1805 1806 /* 1807 * Restore a thread's priority when priority propagation is 1808 * over. The prio argument is the minimum priority the thread 1809 * needs to have to satisfy other possible priority lending 1810 * requests. If the thread's regular priority is less 1811 * important than prio, the thread will keep a priority boost 1812 * of prio. 1813 */ 1814 void 1815 sched_unlend_prio(struct thread *td, u_char prio) 1816 { 1817 u_char base_pri; 1818 1819 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1820 td->td_base_pri <= PRI_MAX_TIMESHARE) 1821 base_pri = td->td_user_pri; 1822 else 1823 base_pri = td->td_base_pri; 1824 if (prio >= base_pri) { 1825 td->td_flags &= ~TDF_BORROWING; 1826 sched_thread_priority(td, base_pri); 1827 } else 1828 sched_lend_prio(td, prio); 1829 } 1830 1831 /* 1832 * Standard entry for setting the priority to an absolute value. 1833 */ 1834 void 1835 sched_prio(struct thread *td, u_char prio) 1836 { 1837 u_char oldprio; 1838 1839 /* First, update the base priority. */ 1840 td->td_base_pri = prio; 1841 1842 /* 1843 * If the thread is borrowing another thread's priority, don't 1844 * ever lower the priority. 1845 */ 1846 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1847 return; 1848 1849 /* Change the real priority. */ 1850 oldprio = td->td_priority; 1851 sched_thread_priority(td, prio); 1852 1853 /* 1854 * If the thread is on a turnstile, then let the turnstile update 1855 * its state. 1856 */ 1857 if (TD_ON_LOCK(td) && oldprio != prio) 1858 turnstile_adjust(td, oldprio); 1859 } 1860 1861 /* 1862 * Set the base user priority, does not effect current running priority. 1863 */ 1864 void 1865 sched_user_prio(struct thread *td, u_char prio) 1866 { 1867 1868 td->td_base_user_pri = prio; 1869 if (td->td_lend_user_pri <= prio) 1870 return; 1871 td->td_user_pri = prio; 1872 } 1873 1874 void 1875 sched_lend_user_prio(struct thread *td, u_char prio) 1876 { 1877 1878 THREAD_LOCK_ASSERT(td, MA_OWNED); 1879 td->td_lend_user_pri = prio; 1880 td->td_user_pri = min(prio, td->td_base_user_pri); 1881 if (td->td_priority > td->td_user_pri) 1882 sched_prio(td, td->td_user_pri); 1883 else if (td->td_priority != td->td_user_pri) 1884 td->td_flags |= TDF_NEEDRESCHED; 1885 } 1886 1887 /* 1888 * Like the above but first check if there is anything to do. 1889 */ 1890 void 1891 sched_lend_user_prio_cond(struct thread *td, u_char prio) 1892 { 1893 1894 if (td->td_lend_user_pri != prio) 1895 goto lend; 1896 if (td->td_user_pri != min(prio, td->td_base_user_pri)) 1897 goto lend; 1898 if (td->td_priority >= td->td_user_pri) 1899 goto lend; 1900 return; 1901 1902 lend: 1903 thread_lock(td); 1904 sched_lend_user_prio(td, prio); 1905 thread_unlock(td); 1906 } 1907 1908 #ifdef SMP 1909 /* 1910 * This tdq is about to idle. Try to steal a thread from another CPU before 1911 * choosing the idle thread. 1912 */ 1913 static void 1914 tdq_trysteal(struct tdq *tdq) 1915 { 1916 struct cpu_group *cg; 1917 struct tdq *steal; 1918 cpuset_t mask; 1919 int cpu, i; 1920 1921 if (smp_started == 0 || trysteal_limit == 0 || tdq->tdq_cg == NULL) 1922 return; 1923 CPU_FILL(&mask); 1924 CPU_CLR(PCPU_GET(cpuid), &mask); 1925 /* We don't want to be preempted while we're iterating. */ 1926 spinlock_enter(); 1927 TDQ_UNLOCK(tdq); 1928 for (i = 1, cg = tdq->tdq_cg; ; ) { 1929 cpu = sched_highest(cg, mask, steal_thresh); 1930 /* 1931 * If a thread was added while interrupts were disabled don't 1932 * steal one here. 1933 */ 1934 if (tdq->tdq_load > 0) { 1935 TDQ_LOCK(tdq); 1936 break; 1937 } 1938 if (cpu == -1) { 1939 i++; 1940 cg = cg->cg_parent; 1941 if (cg == NULL || i > trysteal_limit) { 1942 TDQ_LOCK(tdq); 1943 break; 1944 } 1945 continue; 1946 } 1947 steal = TDQ_CPU(cpu); 1948 /* 1949 * The data returned by sched_highest() is stale and 1950 * the chosen CPU no longer has an eligible thread. 1951 */ 1952 if (steal->tdq_load < steal_thresh || 1953 steal->tdq_transferable == 0) 1954 continue; 1955 tdq_lock_pair(tdq, steal); 1956 /* 1957 * If we get to this point, unconditonally exit the loop 1958 * to bound the time spent in the critcal section. 1959 * 1960 * If a thread was added while interrupts were disabled don't 1961 * steal one here. 1962 */ 1963 if (tdq->tdq_load > 0) { 1964 TDQ_UNLOCK(steal); 1965 break; 1966 } 1967 /* 1968 * The data returned by sched_highest() is stale and 1969 * the chosen CPU no longer has an eligible thread. 1970 */ 1971 if (steal->tdq_load < steal_thresh || 1972 steal->tdq_transferable == 0) { 1973 TDQ_UNLOCK(steal); 1974 break; 1975 } 1976 /* 1977 * If we fail to acquire one due to affinity restrictions, 1978 * bail out and let the idle thread to a more complete search 1979 * outside of a critical section. 1980 */ 1981 if (tdq_move(steal, tdq) == NULL) { 1982 TDQ_UNLOCK(steal); 1983 break; 1984 } 1985 TDQ_UNLOCK(steal); 1986 break; 1987 } 1988 spinlock_exit(); 1989 } 1990 #endif 1991 1992 /* 1993 * Handle migration from sched_switch(). This happens only for 1994 * cpu binding. 1995 */ 1996 static struct mtx * 1997 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1998 { 1999 struct tdq *tdn; 2000 2001 KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: " 2002 "thread %s queued on absent CPU %d.", td->td_name, 2003 td_get_sched(td)->ts_cpu)); 2004 tdn = TDQ_CPU(td_get_sched(td)->ts_cpu); 2005 #ifdef SMP 2006 tdq_load_rem(tdq, td); 2007 /* 2008 * Do the lock dance required to avoid LOR. We grab an extra 2009 * spinlock nesting to prevent preemption while we're 2010 * not holding either run-queue lock. 2011 */ 2012 spinlock_enter(); 2013 thread_lock_block(td); /* This releases the lock on tdq. */ 2014 2015 /* 2016 * Acquire both run-queue locks before placing the thread on the new 2017 * run-queue to avoid deadlocks created by placing a thread with a 2018 * blocked lock on the run-queue of a remote processor. The deadlock 2019 * occurs when a third processor attempts to lock the two queues in 2020 * question while the target processor is spinning with its own 2021 * run-queue lock held while waiting for the blocked lock to clear. 2022 */ 2023 tdq_lock_pair(tdn, tdq); 2024 tdq_add(tdn, td, flags); 2025 tdq_notify(tdn, td); 2026 TDQ_UNLOCK(tdn); 2027 spinlock_exit(); 2028 #endif 2029 return (TDQ_LOCKPTR(tdn)); 2030 } 2031 2032 /* 2033 * Variadic version of thread_lock_unblock() that does not assume td_lock 2034 * is blocked. 2035 */ 2036 static inline void 2037 thread_unblock_switch(struct thread *td, struct mtx *mtx) 2038 { 2039 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 2040 (uintptr_t)mtx); 2041 } 2042 2043 /* 2044 * Switch threads. This function has to handle threads coming in while 2045 * blocked for some reason, running, or idle. It also must deal with 2046 * migrating a thread from one queue to another as running threads may 2047 * be assigned elsewhere via binding. 2048 */ 2049 void 2050 sched_switch(struct thread *td, struct thread *newtd, int flags) 2051 { 2052 struct tdq *tdq; 2053 struct td_sched *ts; 2054 struct mtx *mtx; 2055 int srqflag; 2056 int cpuid, preempted; 2057 2058 THREAD_LOCK_ASSERT(td, MA_OWNED); 2059 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 2060 2061 cpuid = PCPU_GET(cpuid); 2062 tdq = TDQ_SELF(); 2063 ts = td_get_sched(td); 2064 mtx = td->td_lock; 2065 sched_pctcpu_update(ts, 1); 2066 ts->ts_rltick = ticks; 2067 td->td_lastcpu = td->td_oncpu; 2068 td->td_oncpu = NOCPU; 2069 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 2070 (flags & SW_PREEMPT) != 0; 2071 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 2072 td->td_owepreempt = 0; 2073 if (!TD_IS_IDLETHREAD(td)) 2074 tdq->tdq_switchcnt++; 2075 /* 2076 * The lock pointer in an idle thread should never change. Reset it 2077 * to CAN_RUN as well. 2078 */ 2079 if (TD_IS_IDLETHREAD(td)) { 2080 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2081 TD_SET_CAN_RUN(td); 2082 } else if (TD_IS_RUNNING(td)) { 2083 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2084 srqflag = preempted ? 2085 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 2086 SRQ_OURSELF|SRQ_YIELDING; 2087 #ifdef SMP 2088 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 2089 ts->ts_cpu = sched_pickcpu(td, 0); 2090 #endif 2091 if (ts->ts_cpu == cpuid) 2092 tdq_runq_add(tdq, td, srqflag); 2093 else { 2094 KASSERT(THREAD_CAN_MIGRATE(td) || 2095 (ts->ts_flags & TSF_BOUND) != 0, 2096 ("Thread %p shouldn't migrate", td)); 2097 mtx = sched_switch_migrate(tdq, td, srqflag); 2098 } 2099 } else { 2100 /* This thread must be going to sleep. */ 2101 TDQ_LOCK(tdq); 2102 mtx = thread_lock_block(td); 2103 tdq_load_rem(tdq, td); 2104 #ifdef SMP 2105 if (tdq->tdq_load == 0) 2106 tdq_trysteal(tdq); 2107 #endif 2108 } 2109 2110 #if (KTR_COMPILE & KTR_SCHED) != 0 2111 if (TD_IS_IDLETHREAD(td)) 2112 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 2113 "prio:%d", td->td_priority); 2114 else 2115 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 2116 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 2117 "lockname:\"%s\"", td->td_lockname); 2118 #endif 2119 2120 /* 2121 * We enter here with the thread blocked and assigned to the 2122 * appropriate cpu run-queue or sleep-queue and with the current 2123 * thread-queue locked. 2124 */ 2125 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2126 newtd = choosethread(); 2127 /* 2128 * Call the MD code to switch contexts if necessary. 2129 */ 2130 if (td != newtd) { 2131 #ifdef HWPMC_HOOKS 2132 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2133 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 2134 #endif 2135 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 2136 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2137 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2138 sched_pctcpu_update(td_get_sched(newtd), 0); 2139 2140 #ifdef KDTRACE_HOOKS 2141 /* 2142 * If DTrace has set the active vtime enum to anything 2143 * other than INACTIVE (0), then it should have set the 2144 * function to call. 2145 */ 2146 if (dtrace_vtime_active) 2147 (*dtrace_vtime_switch_func)(newtd); 2148 #endif 2149 2150 cpu_switch(td, newtd, mtx); 2151 /* 2152 * We may return from cpu_switch on a different cpu. However, 2153 * we always return with td_lock pointing to the current cpu's 2154 * run queue lock. 2155 */ 2156 cpuid = PCPU_GET(cpuid); 2157 tdq = TDQ_SELF(); 2158 lock_profile_obtain_lock_success( 2159 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2160 2161 SDT_PROBE0(sched, , , on__cpu); 2162 #ifdef HWPMC_HOOKS 2163 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2164 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 2165 #endif 2166 } else { 2167 thread_unblock_switch(td, mtx); 2168 SDT_PROBE0(sched, , , remain__cpu); 2169 } 2170 2171 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2172 "prio:%d", td->td_priority); 2173 2174 /* 2175 * Assert that all went well and return. 2176 */ 2177 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 2178 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2179 td->td_oncpu = cpuid; 2180 } 2181 2182 /* 2183 * Adjust thread priorities as a result of a nice request. 2184 */ 2185 void 2186 sched_nice(struct proc *p, int nice) 2187 { 2188 struct thread *td; 2189 2190 PROC_LOCK_ASSERT(p, MA_OWNED); 2191 2192 p->p_nice = nice; 2193 FOREACH_THREAD_IN_PROC(p, td) { 2194 thread_lock(td); 2195 sched_priority(td); 2196 sched_prio(td, td->td_base_user_pri); 2197 thread_unlock(td); 2198 } 2199 } 2200 2201 /* 2202 * Record the sleep time for the interactivity scorer. 2203 */ 2204 void 2205 sched_sleep(struct thread *td, int prio) 2206 { 2207 2208 THREAD_LOCK_ASSERT(td, MA_OWNED); 2209 2210 td->td_slptick = ticks; 2211 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2212 td->td_flags |= TDF_CANSWAP; 2213 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2214 return; 2215 if (static_boost == 1 && prio) 2216 sched_prio(td, prio); 2217 else if (static_boost && td->td_priority > static_boost) 2218 sched_prio(td, static_boost); 2219 } 2220 2221 /* 2222 * Schedule a thread to resume execution and record how long it voluntarily 2223 * slept. We also update the pctcpu, interactivity, and priority. 2224 */ 2225 void 2226 sched_wakeup(struct thread *td) 2227 { 2228 struct td_sched *ts; 2229 int slptick; 2230 2231 THREAD_LOCK_ASSERT(td, MA_OWNED); 2232 ts = td_get_sched(td); 2233 td->td_flags &= ~TDF_CANSWAP; 2234 /* 2235 * If we slept for more than a tick update our interactivity and 2236 * priority. 2237 */ 2238 slptick = td->td_slptick; 2239 td->td_slptick = 0; 2240 if (slptick && slptick != ticks) { 2241 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2242 sched_interact_update(td); 2243 sched_pctcpu_update(ts, 0); 2244 } 2245 /* 2246 * Reset the slice value since we slept and advanced the round-robin. 2247 */ 2248 ts->ts_slice = 0; 2249 sched_add(td, SRQ_BORING); 2250 } 2251 2252 /* 2253 * Penalize the parent for creating a new child and initialize the child's 2254 * priority. 2255 */ 2256 void 2257 sched_fork(struct thread *td, struct thread *child) 2258 { 2259 THREAD_LOCK_ASSERT(td, MA_OWNED); 2260 sched_pctcpu_update(td_get_sched(td), 1); 2261 sched_fork_thread(td, child); 2262 /* 2263 * Penalize the parent and child for forking. 2264 */ 2265 sched_interact_fork(child); 2266 sched_priority(child); 2267 td_get_sched(td)->ts_runtime += tickincr; 2268 sched_interact_update(td); 2269 sched_priority(td); 2270 } 2271 2272 /* 2273 * Fork a new thread, may be within the same process. 2274 */ 2275 void 2276 sched_fork_thread(struct thread *td, struct thread *child) 2277 { 2278 struct td_sched *ts; 2279 struct td_sched *ts2; 2280 struct tdq *tdq; 2281 2282 tdq = TDQ_SELF(); 2283 THREAD_LOCK_ASSERT(td, MA_OWNED); 2284 /* 2285 * Initialize child. 2286 */ 2287 ts = td_get_sched(td); 2288 ts2 = td_get_sched(child); 2289 child->td_oncpu = NOCPU; 2290 child->td_lastcpu = NOCPU; 2291 child->td_lock = TDQ_LOCKPTR(tdq); 2292 child->td_cpuset = cpuset_ref(td->td_cpuset); 2293 child->td_domain.dr_policy = td->td_cpuset->cs_domain; 2294 ts2->ts_cpu = ts->ts_cpu; 2295 ts2->ts_flags = 0; 2296 /* 2297 * Grab our parents cpu estimation information. 2298 */ 2299 ts2->ts_ticks = ts->ts_ticks; 2300 ts2->ts_ltick = ts->ts_ltick; 2301 ts2->ts_ftick = ts->ts_ftick; 2302 /* 2303 * Do not inherit any borrowed priority from the parent. 2304 */ 2305 child->td_priority = child->td_base_pri; 2306 /* 2307 * And update interactivity score. 2308 */ 2309 ts2->ts_slptime = ts->ts_slptime; 2310 ts2->ts_runtime = ts->ts_runtime; 2311 /* Attempt to quickly learn interactivity. */ 2312 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2313 #ifdef KTR 2314 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2315 #endif 2316 } 2317 2318 /* 2319 * Adjust the priority class of a thread. 2320 */ 2321 void 2322 sched_class(struct thread *td, int class) 2323 { 2324 2325 THREAD_LOCK_ASSERT(td, MA_OWNED); 2326 if (td->td_pri_class == class) 2327 return; 2328 td->td_pri_class = class; 2329 } 2330 2331 /* 2332 * Return some of the child's priority and interactivity to the parent. 2333 */ 2334 void 2335 sched_exit(struct proc *p, struct thread *child) 2336 { 2337 struct thread *td; 2338 2339 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2340 "prio:%d", child->td_priority); 2341 PROC_LOCK_ASSERT(p, MA_OWNED); 2342 td = FIRST_THREAD_IN_PROC(p); 2343 sched_exit_thread(td, child); 2344 } 2345 2346 /* 2347 * Penalize another thread for the time spent on this one. This helps to 2348 * worsen the priority and interactivity of processes which schedule batch 2349 * jobs such as make. This has little effect on the make process itself but 2350 * causes new processes spawned by it to receive worse scores immediately. 2351 */ 2352 void 2353 sched_exit_thread(struct thread *td, struct thread *child) 2354 { 2355 2356 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2357 "prio:%d", child->td_priority); 2358 /* 2359 * Give the child's runtime to the parent without returning the 2360 * sleep time as a penalty to the parent. This causes shells that 2361 * launch expensive things to mark their children as expensive. 2362 */ 2363 thread_lock(td); 2364 td_get_sched(td)->ts_runtime += td_get_sched(child)->ts_runtime; 2365 sched_interact_update(td); 2366 sched_priority(td); 2367 thread_unlock(td); 2368 } 2369 2370 void 2371 sched_preempt(struct thread *td) 2372 { 2373 struct tdq *tdq; 2374 2375 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2376 2377 thread_lock(td); 2378 tdq = TDQ_SELF(); 2379 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2380 tdq->tdq_ipipending = 0; 2381 if (td->td_priority > tdq->tdq_lowpri) { 2382 int flags; 2383 2384 flags = SW_INVOL | SW_PREEMPT; 2385 if (td->td_critnest > 1) 2386 td->td_owepreempt = 1; 2387 else if (TD_IS_IDLETHREAD(td)) 2388 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2389 else 2390 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2391 } 2392 thread_unlock(td); 2393 } 2394 2395 /* 2396 * Fix priorities on return to user-space. Priorities may be elevated due 2397 * to static priorities in msleep() or similar. 2398 */ 2399 void 2400 sched_userret_slowpath(struct thread *td) 2401 { 2402 2403 thread_lock(td); 2404 td->td_priority = td->td_user_pri; 2405 td->td_base_pri = td->td_user_pri; 2406 tdq_setlowpri(TDQ_SELF(), td); 2407 thread_unlock(td); 2408 } 2409 2410 /* 2411 * Handle a stathz tick. This is really only relevant for timeshare 2412 * threads. 2413 */ 2414 void 2415 sched_clock(struct thread *td) 2416 { 2417 struct tdq *tdq; 2418 struct td_sched *ts; 2419 2420 THREAD_LOCK_ASSERT(td, MA_OWNED); 2421 tdq = TDQ_SELF(); 2422 #ifdef SMP 2423 /* 2424 * We run the long term load balancer infrequently on the first cpu. 2425 */ 2426 if (balance_tdq == tdq && smp_started != 0 && rebalance != 0) { 2427 if (balance_ticks && --balance_ticks == 0) 2428 sched_balance(); 2429 } 2430 #endif 2431 /* 2432 * Save the old switch count so we have a record of the last ticks 2433 * activity. Initialize the new switch count based on our load. 2434 * If there is some activity seed it to reflect that. 2435 */ 2436 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2437 tdq->tdq_switchcnt = tdq->tdq_load; 2438 /* 2439 * Advance the insert index once for each tick to ensure that all 2440 * threads get a chance to run. 2441 */ 2442 if (tdq->tdq_idx == tdq->tdq_ridx) { 2443 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2444 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2445 tdq->tdq_ridx = tdq->tdq_idx; 2446 } 2447 ts = td_get_sched(td); 2448 sched_pctcpu_update(ts, 1); 2449 if (td->td_pri_class & PRI_FIFO_BIT) 2450 return; 2451 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2452 /* 2453 * We used a tick; charge it to the thread so 2454 * that we can compute our interactivity. 2455 */ 2456 td_get_sched(td)->ts_runtime += tickincr; 2457 sched_interact_update(td); 2458 sched_priority(td); 2459 } 2460 2461 /* 2462 * Force a context switch if the current thread has used up a full 2463 * time slice (default is 100ms). 2464 */ 2465 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2466 ts->ts_slice = 0; 2467 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2468 } 2469 } 2470 2471 u_int 2472 sched_estcpu(struct thread *td __unused) 2473 { 2474 2475 return (0); 2476 } 2477 2478 /* 2479 * Return whether the current CPU has runnable tasks. Used for in-kernel 2480 * cooperative idle threads. 2481 */ 2482 int 2483 sched_runnable(void) 2484 { 2485 struct tdq *tdq; 2486 int load; 2487 2488 load = 1; 2489 2490 tdq = TDQ_SELF(); 2491 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2492 if (tdq->tdq_load > 0) 2493 goto out; 2494 } else 2495 if (tdq->tdq_load - 1 > 0) 2496 goto out; 2497 load = 0; 2498 out: 2499 return (load); 2500 } 2501 2502 /* 2503 * Choose the highest priority thread to run. The thread is removed from 2504 * the run-queue while running however the load remains. For SMP we set 2505 * the tdq in the global idle bitmask if it idles here. 2506 */ 2507 struct thread * 2508 sched_choose(void) 2509 { 2510 struct thread *td; 2511 struct tdq *tdq; 2512 2513 tdq = TDQ_SELF(); 2514 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2515 td = tdq_choose(tdq); 2516 if (td) { 2517 tdq_runq_rem(tdq, td); 2518 tdq->tdq_lowpri = td->td_priority; 2519 return (td); 2520 } 2521 tdq->tdq_lowpri = PRI_MAX_IDLE; 2522 return (PCPU_GET(idlethread)); 2523 } 2524 2525 /* 2526 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2527 * we always request it once we exit a critical section. 2528 */ 2529 static inline void 2530 sched_setpreempt(struct thread *td) 2531 { 2532 struct thread *ctd; 2533 int cpri; 2534 int pri; 2535 2536 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2537 2538 ctd = curthread; 2539 pri = td->td_priority; 2540 cpri = ctd->td_priority; 2541 if (pri < cpri) 2542 ctd->td_flags |= TDF_NEEDRESCHED; 2543 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2544 return; 2545 if (!sched_shouldpreempt(pri, cpri, 0)) 2546 return; 2547 ctd->td_owepreempt = 1; 2548 } 2549 2550 /* 2551 * Add a thread to a thread queue. Select the appropriate runq and add the 2552 * thread to it. This is the internal function called when the tdq is 2553 * predetermined. 2554 */ 2555 void 2556 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2557 { 2558 2559 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2560 KASSERT((td->td_inhibitors == 0), 2561 ("sched_add: trying to run inhibited thread")); 2562 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2563 ("sched_add: bad thread state")); 2564 KASSERT(td->td_flags & TDF_INMEM, 2565 ("sched_add: thread swapped out")); 2566 2567 if (td->td_priority < tdq->tdq_lowpri) 2568 tdq->tdq_lowpri = td->td_priority; 2569 tdq_runq_add(tdq, td, flags); 2570 tdq_load_add(tdq, td); 2571 } 2572 2573 /* 2574 * Select the target thread queue and add a thread to it. Request 2575 * preemption or IPI a remote processor if required. 2576 */ 2577 void 2578 sched_add(struct thread *td, int flags) 2579 { 2580 struct tdq *tdq; 2581 #ifdef SMP 2582 int cpu; 2583 #endif 2584 2585 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2586 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2587 sched_tdname(curthread)); 2588 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2589 KTR_ATTR_LINKED, sched_tdname(td)); 2590 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2591 flags & SRQ_PREEMPTED); 2592 THREAD_LOCK_ASSERT(td, MA_OWNED); 2593 /* 2594 * Recalculate the priority before we select the target cpu or 2595 * run-queue. 2596 */ 2597 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2598 sched_priority(td); 2599 #ifdef SMP 2600 /* 2601 * Pick the destination cpu and if it isn't ours transfer to the 2602 * target cpu. 2603 */ 2604 cpu = sched_pickcpu(td, flags); 2605 tdq = sched_setcpu(td, cpu, flags); 2606 tdq_add(tdq, td, flags); 2607 if (cpu != PCPU_GET(cpuid)) { 2608 tdq_notify(tdq, td); 2609 return; 2610 } 2611 #else 2612 tdq = TDQ_SELF(); 2613 TDQ_LOCK(tdq); 2614 /* 2615 * Now that the thread is moving to the run-queue, set the lock 2616 * to the scheduler's lock. 2617 */ 2618 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2619 tdq_add(tdq, td, flags); 2620 #endif 2621 if (!(flags & SRQ_YIELDING)) 2622 sched_setpreempt(td); 2623 } 2624 2625 /* 2626 * Remove a thread from a run-queue without running it. This is used 2627 * when we're stealing a thread from a remote queue. Otherwise all threads 2628 * exit by calling sched_exit_thread() and sched_throw() themselves. 2629 */ 2630 void 2631 sched_rem(struct thread *td) 2632 { 2633 struct tdq *tdq; 2634 2635 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2636 "prio:%d", td->td_priority); 2637 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2638 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu); 2639 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2640 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2641 KASSERT(TD_ON_RUNQ(td), 2642 ("sched_rem: thread not on run queue")); 2643 tdq_runq_rem(tdq, td); 2644 tdq_load_rem(tdq, td); 2645 TD_SET_CAN_RUN(td); 2646 if (td->td_priority == tdq->tdq_lowpri) 2647 tdq_setlowpri(tdq, NULL); 2648 } 2649 2650 /* 2651 * Fetch cpu utilization information. Updates on demand. 2652 */ 2653 fixpt_t 2654 sched_pctcpu(struct thread *td) 2655 { 2656 fixpt_t pctcpu; 2657 struct td_sched *ts; 2658 2659 pctcpu = 0; 2660 ts = td_get_sched(td); 2661 2662 THREAD_LOCK_ASSERT(td, MA_OWNED); 2663 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2664 if (ts->ts_ticks) { 2665 int rtick; 2666 2667 /* How many rtick per second ? */ 2668 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2669 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2670 } 2671 2672 return (pctcpu); 2673 } 2674 2675 /* 2676 * Enforce affinity settings for a thread. Called after adjustments to 2677 * cpumask. 2678 */ 2679 void 2680 sched_affinity(struct thread *td) 2681 { 2682 #ifdef SMP 2683 struct td_sched *ts; 2684 2685 THREAD_LOCK_ASSERT(td, MA_OWNED); 2686 ts = td_get_sched(td); 2687 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2688 return; 2689 if (TD_ON_RUNQ(td)) { 2690 sched_rem(td); 2691 sched_add(td, SRQ_BORING); 2692 return; 2693 } 2694 if (!TD_IS_RUNNING(td)) 2695 return; 2696 /* 2697 * Force a switch before returning to userspace. If the 2698 * target thread is not running locally send an ipi to force 2699 * the issue. 2700 */ 2701 td->td_flags |= TDF_NEEDRESCHED; 2702 if (td != curthread) 2703 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2704 #endif 2705 } 2706 2707 /* 2708 * Bind a thread to a target cpu. 2709 */ 2710 void 2711 sched_bind(struct thread *td, int cpu) 2712 { 2713 struct td_sched *ts; 2714 2715 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2716 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2717 ts = td_get_sched(td); 2718 if (ts->ts_flags & TSF_BOUND) 2719 sched_unbind(td); 2720 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2721 ts->ts_flags |= TSF_BOUND; 2722 sched_pin(); 2723 if (PCPU_GET(cpuid) == cpu) 2724 return; 2725 ts->ts_cpu = cpu; 2726 /* When we return from mi_switch we'll be on the correct cpu. */ 2727 mi_switch(SW_VOL, NULL); 2728 } 2729 2730 /* 2731 * Release a bound thread. 2732 */ 2733 void 2734 sched_unbind(struct thread *td) 2735 { 2736 struct td_sched *ts; 2737 2738 THREAD_LOCK_ASSERT(td, MA_OWNED); 2739 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2740 ts = td_get_sched(td); 2741 if ((ts->ts_flags & TSF_BOUND) == 0) 2742 return; 2743 ts->ts_flags &= ~TSF_BOUND; 2744 sched_unpin(); 2745 } 2746 2747 int 2748 sched_is_bound(struct thread *td) 2749 { 2750 THREAD_LOCK_ASSERT(td, MA_OWNED); 2751 return (td_get_sched(td)->ts_flags & TSF_BOUND); 2752 } 2753 2754 /* 2755 * Basic yield call. 2756 */ 2757 void 2758 sched_relinquish(struct thread *td) 2759 { 2760 thread_lock(td); 2761 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2762 thread_unlock(td); 2763 } 2764 2765 /* 2766 * Return the total system load. 2767 */ 2768 int 2769 sched_load(void) 2770 { 2771 #ifdef SMP 2772 int total; 2773 int i; 2774 2775 total = 0; 2776 CPU_FOREACH(i) 2777 total += TDQ_CPU(i)->tdq_sysload; 2778 return (total); 2779 #else 2780 return (TDQ_SELF()->tdq_sysload); 2781 #endif 2782 } 2783 2784 int 2785 sched_sizeof_proc(void) 2786 { 2787 return (sizeof(struct proc)); 2788 } 2789 2790 int 2791 sched_sizeof_thread(void) 2792 { 2793 return (sizeof(struct thread) + sizeof(struct td_sched)); 2794 } 2795 2796 #ifdef SMP 2797 #define TDQ_IDLESPIN(tdq) \ 2798 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2799 #else 2800 #define TDQ_IDLESPIN(tdq) 1 2801 #endif 2802 2803 /* 2804 * The actual idle process. 2805 */ 2806 void 2807 sched_idletd(void *dummy) 2808 { 2809 struct thread *td; 2810 struct tdq *tdq; 2811 int oldswitchcnt, switchcnt; 2812 int i; 2813 2814 mtx_assert(&Giant, MA_NOTOWNED); 2815 td = curthread; 2816 tdq = TDQ_SELF(); 2817 THREAD_NO_SLEEPING(); 2818 oldswitchcnt = -1; 2819 for (;;) { 2820 if (tdq->tdq_load) { 2821 thread_lock(td); 2822 mi_switch(SW_VOL | SWT_IDLE, NULL); 2823 thread_unlock(td); 2824 } 2825 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2826 #ifdef SMP 2827 if (always_steal || switchcnt != oldswitchcnt) { 2828 oldswitchcnt = switchcnt; 2829 if (tdq_idled(tdq) == 0) 2830 continue; 2831 } 2832 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2833 #else 2834 oldswitchcnt = switchcnt; 2835 #endif 2836 /* 2837 * If we're switching very frequently, spin while checking 2838 * for load rather than entering a low power state that 2839 * may require an IPI. However, don't do any busy 2840 * loops while on SMT machines as this simply steals 2841 * cycles from cores doing useful work. 2842 */ 2843 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2844 for (i = 0; i < sched_idlespins; i++) { 2845 if (tdq->tdq_load) 2846 break; 2847 cpu_spinwait(); 2848 } 2849 } 2850 2851 /* If there was context switch during spin, restart it. */ 2852 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2853 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2854 continue; 2855 2856 /* Run main MD idle handler. */ 2857 tdq->tdq_cpu_idle = 1; 2858 /* 2859 * Make sure that tdq_cpu_idle update is globally visible 2860 * before cpu_idle() read tdq_load. The order is important 2861 * to avoid race with tdq_notify. 2862 */ 2863 atomic_thread_fence_seq_cst(); 2864 /* 2865 * Checking for again after the fence picks up assigned 2866 * threads often enough to make it worthwhile to do so in 2867 * order to avoid calling cpu_idle(). 2868 */ 2869 if (tdq->tdq_load != 0) { 2870 tdq->tdq_cpu_idle = 0; 2871 continue; 2872 } 2873 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2874 tdq->tdq_cpu_idle = 0; 2875 2876 /* 2877 * Account thread-less hardware interrupts and 2878 * other wakeup reasons equal to context switches. 2879 */ 2880 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2881 if (switchcnt != oldswitchcnt) 2882 continue; 2883 tdq->tdq_switchcnt++; 2884 oldswitchcnt++; 2885 } 2886 } 2887 2888 /* 2889 * A CPU is entering for the first time or a thread is exiting. 2890 */ 2891 void 2892 sched_throw(struct thread *td) 2893 { 2894 struct thread *newtd; 2895 struct tdq *tdq; 2896 2897 if (td == NULL) { 2898 #ifdef SMP 2899 PCPU_SET(sched, DPCPU_PTR(tdq)); 2900 #endif 2901 /* Correct spinlock nesting and acquire the correct lock. */ 2902 tdq = TDQ_SELF(); 2903 TDQ_LOCK(tdq); 2904 spinlock_exit(); 2905 PCPU_SET(switchtime, cpu_ticks()); 2906 PCPU_SET(switchticks, ticks); 2907 } else { 2908 tdq = TDQ_SELF(); 2909 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2910 tdq_load_rem(tdq, td); 2911 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2912 td->td_lastcpu = td->td_oncpu; 2913 td->td_oncpu = NOCPU; 2914 } 2915 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2916 newtd = choosethread(); 2917 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2918 cpu_throw(td, newtd); /* doesn't return */ 2919 } 2920 2921 /* 2922 * This is called from fork_exit(). Just acquire the correct locks and 2923 * let fork do the rest of the work. 2924 */ 2925 void 2926 sched_fork_exit(struct thread *td) 2927 { 2928 struct tdq *tdq; 2929 int cpuid; 2930 2931 /* 2932 * Finish setting up thread glue so that it begins execution in a 2933 * non-nested critical section with the scheduler lock held. 2934 */ 2935 cpuid = PCPU_GET(cpuid); 2936 tdq = TDQ_SELF(); 2937 if (TD_IS_IDLETHREAD(td)) 2938 td->td_lock = TDQ_LOCKPTR(tdq); 2939 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2940 td->td_oncpu = cpuid; 2941 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2942 lock_profile_obtain_lock_success( 2943 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2944 2945 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2946 "prio:%d", td->td_priority); 2947 SDT_PROBE0(sched, , , on__cpu); 2948 } 2949 2950 /* 2951 * Create on first use to catch odd startup conditons. 2952 */ 2953 char * 2954 sched_tdname(struct thread *td) 2955 { 2956 #ifdef KTR 2957 struct td_sched *ts; 2958 2959 ts = td_get_sched(td); 2960 if (ts->ts_name[0] == '\0') 2961 snprintf(ts->ts_name, sizeof(ts->ts_name), 2962 "%s tid %d", td->td_name, td->td_tid); 2963 return (ts->ts_name); 2964 #else 2965 return (td->td_name); 2966 #endif 2967 } 2968 2969 #ifdef KTR 2970 void 2971 sched_clear_tdname(struct thread *td) 2972 { 2973 struct td_sched *ts; 2974 2975 ts = td_get_sched(td); 2976 ts->ts_name[0] = '\0'; 2977 } 2978 #endif 2979 2980 #ifdef SMP 2981 2982 /* 2983 * Build the CPU topology dump string. Is recursively called to collect 2984 * the topology tree. 2985 */ 2986 static int 2987 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2988 int indent) 2989 { 2990 char cpusetbuf[CPUSETBUFSIZ]; 2991 int i, first; 2992 2993 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2994 "", 1 + indent / 2, cg->cg_level); 2995 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2996 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2997 first = TRUE; 2998 for (i = 0; i < MAXCPU; i++) { 2999 if (CPU_ISSET(i, &cg->cg_mask)) { 3000 if (!first) 3001 sbuf_printf(sb, ", "); 3002 else 3003 first = FALSE; 3004 sbuf_printf(sb, "%d", i); 3005 } 3006 } 3007 sbuf_printf(sb, "</cpu>\n"); 3008 3009 if (cg->cg_flags != 0) { 3010 sbuf_printf(sb, "%*s <flags>", indent, ""); 3011 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 3012 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 3013 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 3014 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 3015 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 3016 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 3017 sbuf_printf(sb, "</flags>\n"); 3018 } 3019 3020 if (cg->cg_children > 0) { 3021 sbuf_printf(sb, "%*s <children>\n", indent, ""); 3022 for (i = 0; i < cg->cg_children; i++) 3023 sysctl_kern_sched_topology_spec_internal(sb, 3024 &cg->cg_child[i], indent+2); 3025 sbuf_printf(sb, "%*s </children>\n", indent, ""); 3026 } 3027 sbuf_printf(sb, "%*s</group>\n", indent, ""); 3028 return (0); 3029 } 3030 3031 /* 3032 * Sysctl handler for retrieving topology dump. It's a wrapper for 3033 * the recursive sysctl_kern_smp_topology_spec_internal(). 3034 */ 3035 static int 3036 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 3037 { 3038 struct sbuf *topo; 3039 int err; 3040 3041 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 3042 3043 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 3044 if (topo == NULL) 3045 return (ENOMEM); 3046 3047 sbuf_printf(topo, "<groups>\n"); 3048 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 3049 sbuf_printf(topo, "</groups>\n"); 3050 3051 if (err == 0) { 3052 err = sbuf_finish(topo); 3053 } 3054 sbuf_delete(topo); 3055 return (err); 3056 } 3057 3058 #endif 3059 3060 static int 3061 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 3062 { 3063 int error, new_val, period; 3064 3065 period = 1000000 / realstathz; 3066 new_val = period * sched_slice; 3067 error = sysctl_handle_int(oidp, &new_val, 0, req); 3068 if (error != 0 || req->newptr == NULL) 3069 return (error); 3070 if (new_val <= 0) 3071 return (EINVAL); 3072 sched_slice = imax(1, (new_val + period / 2) / period); 3073 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 3074 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 3075 realstathz); 3076 return (0); 3077 } 3078 3079 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 3080 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 3081 "Scheduler name"); 3082 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 3083 NULL, 0, sysctl_kern_quantum, "I", 3084 "Quantum for timeshare threads in microseconds"); 3085 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 3086 "Quantum for timeshare threads in stathz ticks"); 3087 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 3088 "Interactivity score threshold"); 3089 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 3090 &preempt_thresh, 0, 3091 "Maximal (lowest) priority for preemption"); 3092 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 3093 "Assign static kernel priorities to sleeping threads"); 3094 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 3095 "Number of times idle thread will spin waiting for new work"); 3096 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 3097 &sched_idlespinthresh, 0, 3098 "Threshold before we will permit idle thread spinning"); 3099 #ifdef SMP 3100 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 3101 "Number of hz ticks to keep thread affinity for"); 3102 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 3103 "Enables the long-term load balancer"); 3104 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 3105 &balance_interval, 0, 3106 "Average period in stathz ticks to run the long-term balancer"); 3107 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 3108 "Attempts to steal work from other cores before idling"); 3109 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 3110 "Minimum load on remote CPU before we'll steal"); 3111 SYSCTL_INT(_kern_sched, OID_AUTO, trysteal_limit, CTLFLAG_RW, &trysteal_limit, 3112 0, "Topological distance limit for stealing threads in sched_switch()"); 3113 SYSCTL_INT(_kern_sched, OID_AUTO, always_steal, CTLFLAG_RW, &always_steal, 0, 3114 "Always run the stealer from the idle thread"); 3115 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 3116 CTLFLAG_MPSAFE | CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 3117 "XML dump of detected CPU topology"); 3118 #endif 3119 3120 /* ps compat. All cpu percentages from ULE are weighted. */ 3121 static int ccpu = 0; 3122 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 3123